Gas turbine engines include compressor, combustor, and turbine sections. Gas turbine engines also include a fuel system that supplies fuel to the combustor and includes a control system that, inter alia, meters the fuel supply. The control system uses knowledge of several parameters that describe bulk fuel properties for various functions, such as metering, performance monitoring, and determining appropriate safety limits. Two of these parameters are the specific gravity and lower heating value of the fuel. The ratio of the lower heating value over the square root of the specific gravity is known as the Wobbe Index. The Wobbe Index serves as an equivalence measure for fuel sources.
U.S. Patent App. No. 2014/0238032 to Fitzgerald et. al. discloses a sensor apparatus and methods for facilitating combustion of a gaseous fuel. The sensor apparatus comprises a combustion apparatus defining a combustion chamber therein. The combustion apparatus is configured to combust a fuel-air mixture within the combustion chamber to produce at least one combustion product. At least one optical diagnostic apparatus is coupled to the combustion apparatus for measuring at least one property of the at least one combustion product within the combustion chamber. A controller is coupled to the at least one optical diagnostic apparatus, and is configured to determine the Wobbe index of the fuel in real-time based on the measured at least one property of the at least one combustion product and pre-determined combustion state data stored within the controller.
The present disclosure is directed toward overcoming one or more of the problems discovered by the inventors or that is known in the art.